This invention relates to a device for damping structure-borne noise vibrations, comprising a number of free-swinging vibration absorbing elements in the form of slats, with different resonance frequencies. The slats are arranged on a common base which can be connected with a body to be damped.
Vibration absorbers of the above-mentioned type are known, for example, from German Patent Document DE 1 071 364 or German Patent Document DE-OS 2 163 798. In the case of these vibration absorbers, the resonance frequency of the individual slats is coordinated with the vibrations of the body to be damped. The slats, which are excited in this manner to carry out resonance vibrations, therefore absorb vibration energy from the body to be damped which, by an appropriate damping of the slats, will finally be converted to heat.
To increase the vibration-damping effect, it is known from European Patent Application EP 0 020 284 B1 to stack plate-shaped slats above one another, with layers of a damping material being arranged between the slats. The individual slats and the damping material are coordinated with one another so that the individual plates vibrate against one another and in the process compress and relax the damping material. In such a resonance vibration absorber, the intermediate layers made of damping material must be relatively thick and soft, in order to avoid excessive coupling between the individual slats, which would change the whole vibration behavior.
It is an object of the present invention to provide a vibration absorber of the above-mentioned type which, while the effect is the same, permits a more compact construction, can be coordinated with a frequency range which is as wide as possible, and requires smaller amounts of damping material than previously.
This object is achieved by the vibration absorber according to the invention which on the one hand has freely swinging slats that are constructed as double slats but are not vibrationally coupled to adjacent double slats and therefore exhibit a defined vibration behavior. On the other hand, to increase the damping of one double slat respectively, a known technology referred to as a "squeezed coating" is used for the damping of bending vibrations of thin metal sheets. In this case, the damping layer is deformed by shearing rather than by compressing or relaxing, so that the damping layers may be extremely thin.
The slats may be arranged either side-by-side in a layer, as, for example, according to German Patent Document DE 2 163 798, or sandwiched above one another, as, for example, corresponding to German Patent Document DE 1 071 364 or European Patent Document EP 0 020 284 B1. In a particularly compact arrangement, several layers having a congruent outer circumference are stacked above one another so that a block of freely swinging double slats is created, which are arranged in a linear and column-shaped manner.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.